STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Gross Margin
Revenues	$ 508,364	$ 676,531
Cost of natural gas	235,729	413,553
Net margin	272,635	262,978
Operating expenses
Operations and maintenance	106,131	106,561
Depreciation and amortization	34,684	31,630
General taxes	15,747	15,782
Total operating expenses	156,562	153,973
Operating income	116,073	109,005
Other income	18	813
Other expense	(455)	(454)
Interest expense, net	(10,847)	(11,169)
Income before income taxes	104,789	98,195
Income taxes	(40,046)	(37,814)
Net income	$ 64,743	$ 60,381
Earnings per share
Basic	$ 1.23	$ 1.15
Diluted	$ 1.22	$ 1.13
Average shares (thousands)
Basic	52,519	52,707
Diluted	53,107	53,446
Dividends declared per share of stock	$ 0.35	$ 0.30